Use the tutorial link from mmnpsrsoskl just above and where it shows sector 3, a partly open door, use that sector to show a partly open slider at right angles to the wall for the "second view". Then your door will slide as someone walks through the door. Instead of overlapping the sectors you make the sector just behind (say 4 or 8) the orig. door. Be sure it is close enough that it does not look like it/you moved forward.

EDGE has sliding doors, too, but they're more like how sliding doors would have originally been in Doom (just a single line that has the texture moved over as necessary, gaining/losing the impassable attribute as necessary as well).